[e_nice1803]

Hey guys I recently helped my friend out with his car 2009 335xi car has 86k. He had a misfire on cylinder 3,6 (p0303,p0306 codes). We decided to replace all spark plugs and replace 2 new coil to cylinder 3 and 6. After that no problem, but this morning he txt me and said the problem has occur again. When he started his car early morning which is cold around 6am he said same codes came up. Can someone please help us out any suggestion???

[LangJai]

Is he having rough idle at cold starts? When the car is warm it drives normal?

[e_nice1803]

Yes rough idle when he starts it up and when it warms up its fine

[=C=]

de ja vu ?

http://www.e90post.com/forums/showthread.php?t=1230554

[Blackbird]

I'm also getting a P0303 cylinder misfire code on my '07 335i. It started when I dropped down a couple of gears (AT) to pass a couple slowpokes on the freeway. The SES light popped on, but nothing felt wrong about the way the car was running. Reset the code to see if it would come back. The next night I ran the car hard again and got the SES light (same code) AND the engine started running very roughly under load (though fine at idle). Shut the car down, restarted, and the roughness and SES light were gone.

Until I get time to troubleshoot this I'm running the car very gently. Had no issues with it today.

Found this E39 diagnostic thread (http://www.bimmerfest.com/forums/sho...d.php?t=500419) that I'll use as far as I can. That probably means checking coolant color, swapping coils, checking plug seating, fuel injector cleaning, and cleaning the MAF. Anything beyond that is more than I can tackle.

The challenge is inducing the issue again. Presumably running the car hard will cause it, but I don't want to be too far from home when I do.

[BSM n54iS]

Look above at all the sticky threads ^^^^^^^ The answers gotta be in here somewhere
http://www.e90post.com/forums/showthread.php?t=631829

[bloppitybloop]

Please, make more threads asking the same question which has already been answered.

[Dominasian335]

if you are running increased boost, make sure you step your plugs and gap them properly for boost you are running. Don't buy cheap coils as they don't hold enough power and misfire. NGK plugs and Bosch coils if you are tuned, everything else will give you trouble higher than stage 2

[=C=]

New Bosch plugs should already be gapped...

[Mike@N54Tuning.com]

Originally Posted by =C=

New Bosch plugs should already be gapped...

+1

Only the NGK plugs need to be gapped.

Mike